Mostly overlooked in Apple's quarterly report dealing with sales and revenues is the remarkable -- in some cases, astonishing -- growth in Apple's cloud-based services, ranging from the four trillion notifications sent to iOS users through Notification Center to the record-breaking $2.1 billion profit for iTunes. Users now send over two billion iMessages per day -- bypassing the cellular carriers' biggest profit center, SMS messaging -- from over 500 million devices, and over 250 million users now have iCloud accounts.

The iTunes Store of course is Apple's biggest online success story outside the online Apple Store itself, now available in 119 countries and offering a catalog of 20 million songs. In December alone, downloads topped two billion for the first time, and Apple says it has 500 million account holders, over 80 percent of whom have credit cards on file with Apple. The App Store offers 775,000 applications to choose from, surpassed 40 billion downloads in 2012, and has paid out over $7 billion to developers. Game Center, Apple's own game-centered score and achievement sync and social engine, has over 200M users.

The company's disruptive Messages service -- which allows iOS and Mac owners to exchange SMS-like multimedia messages to each other without incurring cellular texting charges -- has now sent over 450 billion messages, with an average of two billion (and growing) per day. In addition, iCloud offers free syncing of contacts, calendar data, bookmarks, reminders, notes, email and other data to mostly Mac and iOS owners (though the service is also available to Windows users), along with security in the form of Find My iPhone -- which offers a "lost mode," passcode locking, alerts and messages to help recover a misplaced iPhone and GPS tracking or remote wiping if the iOS device has been stolen.

More remarkably, all the features listed (and the company offers other services beyond what has been mentioned) are given away for free, unlike it's $100-per-year predecessor (though the older service did offer some features no longer supported, such as free website hosting). The service is so popular that, like with Google, any minor interruption in service -- no matter how small or temporary -- makes headlines and produces howls from affected users.

Just over a year since its initial launch (replacing the Mobile Me service, which was later shuttered entirely), iCloud has become an essential part of both the iOS and Mac experience. Across 2012, the service grew from 85 million users to over 250 million. Apple CEO Tim Cook has referred to the cloud-based suite as "a strategy for the next decade."

Users who need more storage space for documents can pay for that, though services such as Dropbox offer more flexibility. More Mac and iOS programs, such as word processor iaWriter, are now offering automatic backup of documents into iCloud and other services.

Apple offers another paid service called iTunes Match, which supplements the automatic "backup" of all iTunes purchases by expanding to cover up to 25,000 non-iTunes songs as well, making a users' entire library available for spontaneous streaming or downloading on demand on all their devices. While Apple has not broken out figures from iTunes Match in terms of either revenue or users, it is thought that the company runs the service at break-even, and spends much of the revenue in royalties given to the artists whose work is streamed.

The company is also rumored to be launching a Pandora-like subscription radio service sometime this year, though apart from some negotiations with record companies, little solid evidence has emerged of any near-term launch. Apple CEO Tim Cook was recently quoted as saying that Apple prefers to continue "adding value" to the software and services it offers its customers rather than frequently replacing hardware.